Improve scan conversion rules 4 and 6.
Two new constraints are introduced to better identify a `stub' -- a
concept which is only vaguely described in the OpenType
specification. The old code was too rigorous and suppressed more
pixel than it should.
. The intersection of the two profiles with the scanline is less
than a half pixel. Code related to this was already present in
the sources but has been commented out.
. The endpoint of the original contour forming a profile has a
distance (`overshoot') less than half a pixel to the scanline.
Note that the two additional conditions fix almost all differences
to the Windows rasterizer, but some problematic cases remain.
* src/raster/ftraster.c (Overshoot_Top, Overshoot_Bottom): New
macros for the `flags' field in the `TProfile' structure.
(IS_BOTTOM_OVERSHOOT, IS_TOP_OVERSHOOT): New macros.
(New_Profile, End_Profile): Pass overshoot flag as an argument and
set it accordingly.
Update callers.
(Vertical_Sweep_Drop, Horizontal_Sweep_Drop): Implement the two new
constraints.
2 files changed